1 /* $OpenBSD: polevll.c,v 1.2 2013/11/12 20:35:09 martynas Exp $ */
2
3 /*
4 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /* polevll.c
20 * p1evll.c
21 *
22 * Evaluate polynomial
23 *
24 *
25 *
26 * SYNOPSIS:
27 *
28 * int N;
29 * long double x, y, coef[N+1], polevl[];
30 *
31 * y = polevll( x, coef, N );
32 *
33 *
34 *
35 * DESCRIPTION:
36 *
37 * Evaluates polynomial of degree N:
38 *
39 * 2 N
40 * y = C + C x + C x +...+ C x
41 * 0 1 2 N
42 *
43 * Coefficients are stored in reverse order:
44 *
45 * coef[0] = C , ..., coef[N] = C .
46 * N 0
47 *
48 * The function p1evll() assumes that coef[N] = 1.0 and is
49 * omitted from the array. Its calling arguments are
50 * otherwise the same as polevll().
51 *
52 *
53 * SPEED:
54 *
55 * In the interest of speed, there are no checks for out
56 * of bounds arithmetic. This routine is used by most of
57 * the functions in the library. Depending on available
58 * equipment features, the user may wish to rewrite the
59 * program in microcode or assembly language.
60 *
61 */
62
63
64 /*
65 * Polynomial evaluator:
66 * P[0] x^n + P[1] x^(n-1) + ... + P[n]
67 */
68 long double
__polevll(long double x,const long double * P,int n)69 __polevll(long double x, const long double *P, int n)
70 {
71 long double y;
72
73 y = *P++;
74 do {
75 y = y * x + *P++;
76 } while (--n);
77
78 return (y);
79 }
80
81 /*
82 * Polynomial evaluator:
83 * x^n + P[0] x^(n-1) + P[1] x^(n-2) + ... + P[n]
84 */
85 long double
__p1evll(long double x,const long double * P,int n)86 __p1evll(long double x, const long double *P, int n)
87 {
88 long double y;
89
90 n -= 1;
91 y = x + *P++;
92 do {
93 y = y * x + *P++;
94 } while (--n);
95
96 return (y);
97 }
98
